Tranny problems, PO 741 code

I was pulling my boat home from the lake and couldnt get my transmission to work in 3-4. I can put it in od but as soon as it comes into 3rd or should I say it will not go into 3rd gear. Low and 2nd work fine. I had to drive home in 2nd gear. We got home and my friend hooked up to get a code for me to go by. It was reading code PO741 Torque Converter CKT performance or shut off. When I looked this up on line im getting so many causes that I thought Id just see if anyone has had this problem and what you done to correct it outside of taking it to the shop...Help!